This invention relates to mechanisms for coupling compound shift levers together for use in transmissions. More particularly, this invention relates to damper assemblies adapted to absorb, and hence to isolate, noise and vibrations which emanate from the transmission of a vehicle.
Numerous damper assemblies for absorbing noise and vibrations have been designed for compound shift lever assemblies, particularly for use in heavy trucks. It is well known to provide rubber or elastomeric materials in joints or connections between upper and lower levers of compound shift levers. A great number of such damper assemblies, however, employ such elastomeric materials between selective portions of relatively complex apparatus. For example, in one compound shift lever device a metallic female extension is attached to a lower portion of an upper male lever to co-axially fix the upper lever to a lower male lever. The metallic extension is threaded, and contains a bore lined with elastomer into which a lower extremity of the upper portion extends. Enshrouded about the coupled levers is an elastomeric boot to enhance vibration absorption capability. Such conventional devices are typical; yet they have been unsatisfactory for lack of simplicity. As a result, such damper systems are often prone to early failures; perhaps such failures have often been statistically introduced into their manufacture via mere complexity.
It would be desireable to provide a shift lever assembly with a vibration and noise damper to isolate noise from the cabin of a truck or other vehicle without the use of complex parts. It would be particularly desirable to completely isolate upper and lower shift levers from vibrations and noise inherent in metal to metal contact via employment of a simple two-piece damper assembly.